Subthalamic nucleus deep brain stimulation: an invaluable role for MER.

INTRODUCTION: Subthalamic nucleus (STN) deep brain stimulation (DBS) is currently the main surgical procedure for medically refractory Parkinson's disease. The benefit of intra-operative microelectrode recording (MER) for the purpose of neurophysiological localization and mapping of the STN continues to be debated. METHODS: A retrospective review of the charts and operative reports of all patients receiving STN DBS implantation for Parkinson's disease at our institution from January 2004 to March 2011 was done. RESULTS: Data from 43 of 44 patients with Parkinson's disease treated with STN DBS were reviewed. The average number of tracts on the left was 2.4, versus 2.3 on the right. The average dorsal and ventral anatomical boundaries of the STN based on Schaltenbrand's Stereotactic Atlas were estimated to be at -5.0 mm above and +1.4 mm below target respectively. The average dorsal and ventral boundaries of the STN using MER were -2.6 mm above and +2.0 mm below target respectively. The average dorsal-ventral distance of the STN as predicted by Stereotactic Atlas was 6.4 mm, compared to 4.6 mm as determined by MER. MER demonstrated the average dorsal and ventral boundaries on the left side were -2.6 mm and +2.2 mm from target respectively, while the average dorsal and ventral boundaries on the right side were -2.5 mm and +1.8 mm from target respectively with MER. CONCLUSIONS: MER in STN DBS surgery demonstrated measurable difference between stereotactic atlas/MRI STN target and neurophysiologic STN localization.

Reinnervation of skeletal muscle in the tongue by preganglionic parasympathetic vagal neurons.

Reinnervation of the skeletal muscle in the tongue following vago-hypoglossal anastomosis was studied by means of retrograde labelling with horseradish peroxidase and anterograde labelling with the autoradiographic tracing method combined with acetylcholinesterase staining for motor endplates. The proximal stump of the transected vagus nerve was anastomosed to the distal stump of the transected hypoglossal nerve in the neck, or in the thorax below the emergence of the recurrent laryngeal fibres. After 2-3 months, reinnervation of the tongue by vagal fibres was studied. Control cases in which the hypoglossal nerve was transected, but anastomosis was not performed, revealed that innervation of the lingual muscle is derived entirely from the hypoglossal nerves. Following unilateral vago-hypoglossal anastomosis a reduced number of fine nerve fibres terminated in relation to the acetylcholinesterase-stained endplates on the side of the anastomosis. At no time were fibres on either side observed to form sprouts which crossed the midline. Horseradish peroxidase (HRP) was injected into the tongue to determine the origin of the fibres that reinnervated the lingual muscle following anastomosis. On the side of the anastomosis, HRP-labelled neurons were present within the dorsal motor nucleus of the vagus and were absent from the hypoglossal nucleus. When the anastomosis was performed in the neck, neurons within the nucleus ambiguous were also labelled with HRP, but this was not observed following anastomosis in the thorax below the recurrent laryngeal nerve. When tritiated amino acids were injected into the dorsal motor nucleus of the vagus, the motor endplates on the anastomosed side of the tongue were labelled autoradiographically. This labelling could not be abolished by transecting both hypoglossal nerves, confirming that the labelling was due to reinnervation by vagal fibres. It is concluded that anastomosis of the proximal end of the transected vagus nerve to the distal end of the transected hypoglossal nerve is followed by regeneration of the vagal fibres which cross the anastomosis and reinnervate the denervated motor endplates in the tongue. The cell bodies of origin are located within the dorsal motor nucleus of the vagus and are preganglionic parasympathetic neurons.

Numbers of metrial gland cells in the placental labyrinth of congenic resistant and inbred strains of mice, with observations on the size of the labyrinth.

The size of the placental labyrinth and the number of metrial gland cells in it were investigated, from the eleventh to the sixteenth day of gestation, in C57BL/10Sn, B10.A/SgSn, SWR/J and DBA/2J isogenic matings and C57BL/10Sn X B10.A/SgSn and B10.A/SgSn X C57BL/10Sn congenic matings. It was found that both H-2 disparity between mother and conceptus and some other strain-specific trait under genetic control influence the size of the placental labyrinth, while the number of labyrinthine metrial gland cells is affected only by the strain-specific trait.

Mononuclear cell accumulations in the trophoblastic giant cell circulation in inbred strains of mice.

Marked accumulations of mononuclear cells in the trophoblastic giant cell layer of the pregnant mouse uterus have been investigated in the B10, B10.A, SWR/J and DBA/2J strains. Relatively low and approximately equal numbers of mononuclear cells in the trophoblastic giant cell layer were found throughout the ninth and eleventh days in conceptuses of both isogenically mated B10 female mice and those mated with B10.A males. Increased numbers of mononuclear cells in the trophoblastic giant cell layer were found throughout the tenth day in conceptuses of the former mating, while an even greater increase was found at approximately 9 am. on the tenth day in conceptuses of the latter. Conceptuses from B10.A females mated with B10 males have a higher number of mononuclear cells at about 9 am. on the tenth day than those from isogenically mated B10.A females, although the numbers are not as high as those found in conceptuses from B10 females mated with B10.A males. There appears to be no significant difference in numbers of mononuclear cells, at about 6 am, 9 am. and noon on the tenth day, between conceptuses from isogenically mated B10, B10.A, SWR/J and DBA/2J female mice.

Numbers of metrial gland cells in the maternal placental supply and drainage vessels of Swiss Webster and C57B1 mice.

The number of metrial gland cells in the maternal placental supply vessels was found to be greater in C57B1 than in Swiss Webster mice from the eleventh to the thirteenth day of gestation. Since it has been found previously that the number of these cells lodged in the labyrinth is greater in Swiss Webster than in C57B1 mice, it appears likely that more disintegrate in the C57B1 than in the Swiss Webster strain. However, some cells in both strains were found in the veins draining the placenta and uterine wall and have been observed previously in lung capillaries. Disintegration is not, therefore, the sole mechanism of loss. The increase, with time, in the number of metrial gland cells in the metrial gland portion of the placental supply vessels in both strains suggests that, although there is overlap, the decidua basalis is the early source of migrating metrial gland cells, and that the metrial gland later augments the flow.

Microstructural organization of human and bovine cruciate ligaments.

Human and bovine anterior cruciate ligaments studied with the SEM demonstrate fascicular bundle and connective tissue sheath components. In the human, collagen fibers of the connective tissue sheath, although approximately the same diameter as the fascicular fibers, have an orientation suggestive of a binding rather than a tensile function. While both elements have tensile properties, it is hypothesized that the contribution from the sheath component is minimal and, consequently, detailed studies of the tensile properties of ligaments will produce meaningful data when related to the appropriate cross-sectional areas. In direct contrast to the human counterpart, the SEM appearance of bovine cruciate ligaments is tendon-like, characterized by very dense subfasciculi surrounded by very thin connective tissue sheaths.